1. Technical Field
The present inventions relate to switching amplifiers and, more particularly, relate to digital switching amplifiers employing pulse width modulation and closed loop feedback.
2. Description of the Related Art
When audio amplifiers are switched on and off, audible clicks and pops are often heard through speakers. This is not only annoying but gives a user a feeling of low quality equipment. It can also cause the feeling of damage being done to the components. Various approaches such as switching relays have been implemented to eliminate these clicks and pops.
One known type of audio amplifier is a digital PWM amplifier. Digital PWM amplifiers have high power efficiency, resulting in low current and reduced heat. Digital PWM amplifiers operate in the digital domain using digitally generated PWM signals. These digital PWM amplifiers are suitable for digitally integrated systems and can save cost. Although methods exist for quiet power up and power down of open loop digital PWM modulators, eliminating clicks and pops in closed loop digital PWM amplifiers is more difficult.
What is needed are efficient techniques to eliminate clicks and pops at power-up and power-down in closed loop digital PWM amplifiers.